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Ice sheet modelling, topography and uncertainty (TopIce)

English title Ice sheet modelling, topography and uncertainty (TopIce)
Applicant Purves Ross
Number 109449
Funding scheme Project funding (Div. I-III)
Research institution Geographisches Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.10.2005 - 30.09.2007
Approved amount 93'589.00
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Keywords (11)

Topography; Digital Terrain Models; Ice-sheet modelling; Uncertainty; Mass-balance; Inception; Glaciology; Ice sheet modelling; DEM; mass balance; ablation

Lay Summary (English)

Lead
Lay summary
Ice sheet modelling requires the simulation of a complex dynamic system. Due to limiting physi-cal assumptions and high computational demands, ice sheet models (ISM) often run at low reso-lutions of 5-20km. Uncertainties are therefore introduced to the model results both because certain processes cannot be well resolved and through interpolation and approximation.
Monte Carlo Simulations of the reconstruction of the Fennoscandian ice sheet through the last glacial maximum with spatial autocorrelated errors with standard deviations of the range of 18-50m (Value of StDev of error of GLOBE data taken from literature) using the GLIMMER ISM resulted in deviations of modelled ice sheet extent and volume of 5-20%. These deviations are negatively correlated with ice sheet size, emphasizing the large impact of topographic uncertain-ties on modelled ice sheet initiation and configuration early in model runs. Further analysis of errors in GTOPO30 data of Patagonia using SRTM 90 as ground truth has however revealed much larger variations (30-400m) in elevation values than those suggested by GLOBE meta-data. Furthermore, the effect of generalisation of high resolution topography to scales of 5-10km in mountainous terrain (Switzerland, Patagonia) revealed that uncertainties were highly de-pendant on altitude and of the range of 50-400m. These results emphasize that results of large scale models contain significant uncertainties and that scaling is a non trial issue.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
100054 Ice sheet modelling, topography and uncertainty (TopIce) 01.10.2003 Project funding (Div. I-III)

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